1. Field of the Invention
This invention generally relates to a sheet material dispenser and, more particularly, to a novel dispenser for, and method of, efficiently and safely dispensing sheet wrapping material. Additionally, this invention relates to a novel cutting element for use in such dispensers as well as to a novel method of wrapping items.
2. Description of the Prior Art
Dispensers for sheet wrapping materials, such as plastic film, metal foil, waxed paper, paper, or similar wrapping stock, have been well known for both domestic and commercial use. The sheet material was generally wound about a supply roll mounted for rotation in a conventional polygonal container or box that was typically held in one's hand for domestic wrapping purposes, or that rested flatly on a supporting surface for commercial wrapping purposes.
The material was typically furnished in large-sized and large-capacity rolls having lengths of at least 100 ft. and sometimes 1000 ft. or longer, and having widths on the order of 12" or 18" and more, depending on the particular wrapping requirements. A free end portion of the material was generally grasped by a user with one or both hands, who then manually withdrew the material in a taut condition from the box and thereupon urged the material against a fixed, constantly exposed, cutting edge that was conventionally provided on the box, usually along one of the outer edges or walls of the same, in order to sever the material. The conventional cutting edge was serrated and had a row of generally triangularly-shaped teeth whose apices were colinear. Representative dispensers and cutting edges of this general type were disclosed, for example, in the following patents:
______________________________________ U.S.L.P. 1,907,922 U.S.L.P. 3,237,826 U.S.L.P. 2,613,879 U.S.L.P. 3,281,034 U.S.L.P. 2,850,157 U.S.L.P. 3,549,066 U.S.L.P. 2,861,753 U.S.L.P. 3,565,307 U.S.L.P. 3,028,060 U.S.L.P. 3,845,894 U.S.L.P. 3,088,640 U.S.L.P. 4,095,730 U.S.L.P. 3,144,970 ______________________________________
Paper dispensers which did not use a box but, instead, mounted the roll of paper in a drawer, or on a wall mount or a board were disclosed, for example, in the following patents:
U.S. Pat. No. 833,470 PA2 U.S. Pat. No. 3,915,364
However, the satisfactory and safe dispensing of many sheet wrapping materials, particularly thin plastic films, has been the source of many difficulties. It is very desirable, particularly in repetitive commercial wrapping operations, to place the item to be wrapped directly in front, and in the center, of the dispenser which, in turn, is resting on a flat supporting surface. Thereupon, it is preferable to withdraw the plastic film in a taut condition from the dispenser above an upright cutting edge and to subsequently lower the taut film over the cutting edge to cut the film and, in the same downward motion, to lower the cut film onto the item to be wrapped.
However, experience has shown that when taut film was pulled downwardly at a right angle onto the planar, upright, serrated cutting edge whose teeth apices were colinear, it was difficult to cleanly and effortlessly cut the film in a single downward stroke. For user safety reasons, the height of the individual teeth on a conventional serrated cutting edge was made small, usually on the order of 1/16", as measured perpendicularly from the base of each tooth to its apex, and it had been found to require a great deal of initial force on the part of the user to start to sever the film when the entire width of the same is urged at once onto all the teeth. It was very difficult, if not virtually impossible, to urge the withdrawn film along its entire width at a right angle across the entire cutting edge and to effortlessly cut the film with a single downward stroke, especially when a film of substantial length and width was involved.
Hence, most users resorted to cutting the plastic film progressively from one side to the other, e.g. from right to left, across the width of the film in a sawing-type manner. The user thus tilted the film and presented it to the cutting edge in a fashion such that the plane of the taut film formed an acute angle with the cutting edge. With this cutting technique, however, the cut film did not immediately lie in a plane above the item being wrapped, but, rather, was located laterally offset to the side of the box, thus requiring the user to perform another motion, i.e. to bring the cut film back from its offset position to a position directly above the item being wrapped, and thereupon to lower it onto the item. This not only wasted time and required an additional wasted motion and effort, but also was made a much more difficult task due to the physical static cling properties of the plastic film itself. The plastic films, such as copolymers of vinylidine chloride and vinyl chloride, which are popular and well suited for wrapping purposes due to their clinging characteristics, also, unfortunately, have a great tendency to cling to themselves and the adjacent surfaces of their box and other adjacent surfaces. The self-clinging nature of the plastic film, aided by the ever-present electrostatic forces generated at the surface of the film during its withdrawal, caused the plastic film to adhere to itself. Moreover, when the plastic film was moved from its laterally offset position at the side of the box back to its desired central position directly over the item being wrapped at the center of the box, air currents were generated by this movement, and these air currents displaced the film and further aggravated the self-adhering problem and required the user, from time to time, to unpeel and pull apart the portions of the plastic film that clung together. This, of course, was time consuming, annoying, and terribly inefficient, particularly for repetitive commercial wrapping purposes.
Furthermore, the exposed cutting edge was a safety hazard which could severely cut and lacerate the user's hands, particularly when the user was compelled to work with a constantly exposed cutting edge, and had to exert a relatively large amount of force to initiate the cutting, as well as to apply a sawing motion to the material. An additional safety problem resided in the rough handling of dispensers. From time to time, it happened that a dispenser fell, or was shoved from one place to another. In either case, the exposed cutting edge could injure the worker who reached for the falling or shoved dispenser.
Aside from all of the aforementioned drawbacks, it was very difficult to obtain a clean straight cut across the entire width of the film. In most cases, the cut was askew, and the film was usually pulled and stretched to facilitate the cutting action. To remedy this situation, some users resorted to laying the withdrawn plastic film over the exposed cutting edge and then suddenly brought their hands down sequentially across the film in a karate-chop manner. Of course, by repetitively and forcefully bringing their hands down across the film near the exposed cutting edge, the safety problem was magnified.
Still another problem with prior art dispensers was the tendency on the part of plastic film to draw back into the box after being cut. It was somewhat awkward and inefficient to have to grope in the box for the loose free end when this occurred.
In an attempt to solve at least some of the aforementioned problems, it was disclosed in the prior art, for example, in
______________________________________ U.S.L.P. 3,311,278 U.S.L.P. 4,196,647 U.S.L.P. 3,419,201 U.S.Des.L.P. 208,102 ______________________________________
to clamp the sheet material transversely at locations slightly in front of and behind a serrated cutting edge whose apices were colinearly arranged in a row transversely spanning the material, and thereupon manually to move the material relative to the cutting edge, or the cutting edge relative to the material, to cause the material to be severed in a guillotine-type manner across its entire width while clamped fore and aft of the cutting edge. However, the guillotine-type dispenser, although generally satisfactory in terms of properly positioning a cut film directly above the item being wrapped, has proven to be slow in operation because of the requirement of an extra manual motion. After the film was withdrawn from its box, it was necessary to effect the aforementioned fore and aft manual clamping and relative movement between the cutting edge and the material, typically by manually pushing down an actuator member hinged to an upper part of the box. In the event that the user employed both hands to withdraw the film, then the user was required to release the film to perform the extra manual downward movement. The guillotine-type dispensers were not only slow in use and expensive to manufacture, but also proved not to be sufficiently reliable, particularly in a commercial setting.
Dispensers of pressure-sensitive, strip-shaped tape, coupons, and the like were also well known, and were disclosed, for example, in the following references:
______________________________________ U.S.L.P. 2,484,673 U.S.L.P. 3,102,671 U.S.L.P. 2,663,369 U.S.L.P. 3,142,426 U.S.L.P. 2,776,095 U.S.L.P. 3,625,100 U.S.L.P. 2,802,527 U.S.L.P. 3,991,923 U.S.L.P. 2,889,975 British Patent No. 1,256,441 U.S.L.P. 2,921,493 German Patent No. 248,753 U.S.L.P. 2,992,582 Official Gazette, Vol. 767, June 13, 1961, page 290 ______________________________________
However, dispensers for pressure-sensitive tape which typically have a cloth, paper or plastic backing, and a tacky adhesive on one or both sides of the backing, are structurally and functionally quite different from dispensers for sheet wrapping material due, in large part, to the different properties of the materials being dispensed. For example, the tape backings are made of a sturdy material, as opposed to the limp, non-self-supportable nature of thin, broad, sheet wrapping material, such as plastic film, metal foil, waxed paper, paper or the like.